Apparatus for treating webs of filtering material for tobacco product filters, particularly cigarette filters

Abstract

Improved apparatus for treating a web of fibrous material, usually paper, to render it particularly suitable for making filter plugs for cigarettes, including at least one first pair of meshing rotating rolls provided with longitudinal grooves alternating with longitudinal ribs, which engage the paper and stretch it longitudinally in closely spaced successive narrow transverse areas to loosen and expose fibers without impairing the longitudinal continuity of the paper, and at least one second pair of meshing rotating rolls provided with circumferential grooves alternating with circumferential ribs, which engage the paper and groove it in a direction parallel to its travel while also stretching it transversely to further loosen and expose fibers without impairing the transverse continuity of the web. Preferably the apparatus also includes means for moistening the paper in advance of its passage through the rolls and for drying it after its passage therethrough. Means responsive to the tension on the web also are provided for adjusting the speed of the first pair of rolls relative to the second pair.

We claim: 
     
       1. Apparatus for treating an elongated web of fibrous material to render the same particularly adapted to be gathered transversely and enclosed in a wrapper to make a filter cord subdividable into filter rods and filter plugs for cigarettes, comprising: a first group of a pair of meshing rotating rolls provided with narrow longitudinal grooves alternating with narrow longitudinal ribs, said grooves and ribs being parallel to the axes of said rolls, said ribs being adapted to engage a web of fibrous material passed through the bight between said rolls and to prevent appreciable longitudinal contraction of the web so that the latter is stretched longitudinally in closely-spaced successive narrow transverse areas to loosen and expose fibers in such areas without substantial impairment of the longitudinal continuity of the web;   a second group of meshing rotating rolls provided with narrow circumferential grooves alternating with narrow circumferential ribs adapted to engage a web of fibrous material passed through the bight between said rolls and to prevent appreciable lateral contraction of the web so that the web is grooved in a direction parallel to its travel and stretched transversely of the grooves in a plurality of closely-spaced narrow longitudinal areas to loosen and expose fibers in such areas without substantial impairment of the transverse continuity of the web; and   means for advancing a web of fibrous material successively through the bights between the rolls of said first and second group.   
     
     
       2. Apparatus according to claim 1 including means for moistening the material in advance of its passage through the bight between the rolls of the first group; and means for heating the material to substantially dry the same as it emerges from the bight between said second group.   
     
     
       3. Apparatus according to claim 1 including means for moistening the material in advance of its passage through the bight between the rolls of the first group; and means for heating the material, including the rolls of one of the groups, to at least partly dry the material during its passage through the bights between the rolls of the first and second group.   
     
     
       4. Apparatus according to claim 1 including means for moistening the material in advance of its passage through the bight between the rolls of the first group; and means for heating the material to substantially dry the same as it emerges from the bight between said second group, and   means for heating at least one of the rolls of the said second group of rolls.   
     
     
       5. Apparatus according to claim 1 wherein the said means for advancing a web comprise at least one driven roll of the said first group of rolls and driven rolls of the said second group of rolls, and   means for adjusting the circumferential speed of the said first group of rolls relatively to said second group of rolls.   
     
     
       6. Apparatus according to claim 1 wherein the said means for advancing a web comprise at least one driven roll of the said first group of rolls and driven rolls of the said second group of rolls   a common adjustable driving assembly (50, 51, 53) for one of the groups of rolls, and   an adjustable speed adjusting member (59) for the other group of rolls not connected to said driving assembly.   
     
     
       7. Apparatus according to claim 1 wherein the said means for advancing a web comprise at least one driven roll of the said first group of rolls and driven rolls of the said second group of rolls   a common adjustable driving assembly (50, 51, 53) for one of the groups of rolls and   an adjustable speed adjusting member (59) for the other group of rolls not connected to the said driving assembly, and   means including a tension gauge on the web of material entering the said second group of rolls (8, 9, 10) which influences the setting of the speed adjusting member (59) for the drive of the preceding first group of rolls (6, 7).   
     
     
       8. A plant for producing wrapped filter rods containing a filter of fibrous material, consisting of an apparatus for treating an elongated web of fibrous material to render the same particularly adapted to be gathered transversely and of a rod making machine for enclosing the gathered web in a wrapper to make a filter cord subdivided into filter rods for making filter plugs for cigarettes, comprising: a first group of a pair of meshing rotating rolls provided with narrow longitudinal grooves alternating with narrow longitudinal ribs, said grooves and ribs being parallel to the axes of said rolls, said ribs being adapted to engage a web of fibrous material passed through the bight between said rolls and to prevent appreciable longitudinal contraction of the web so that the latter is stretched longitudinally in closely-spaced successive narrow transverse areas to loosen and expose fibers in such areas without substantial impairment of the longitudinal continuity of the web;   a second group of meshing rotating rolls provided with narrow circumferential grooves alternating with narrow circumferential ribs adapted to engage a web of fibrous material passed through the bight between said rolls and to prevent appreciable lateral contraction of the web so that the web is grooved in a direction parallel to its travel and stretched transversely of the grooves in a plurality of closely-spaced narrow longitudinal areas to loosen and expose fibers in such areas without substantial impairment of the transverse continuity of the web; and   means for advancing a web of fibrous material successively through the bights between the rolls of said first and second group including a common adjustable driving assembly for one of the group of rolls and an adjustable speed adjusting member for the other group of rolls, and   a tension gauge on the web of material entering the rod making machine which is influencing the said adjustable driving assembly.   
     
     
       9. A plant according to claim 8 wherein the said driving assembly is determining the operation speed of the rod making machine. 
     
     
       10. A plant according to claim 8 wherein the said speed adjusting member is influenced by a tension gauge on the said web entering the said second group of rolls.